Cyclic redundancy check (CRC) false detection reduction in communication systems

ABSTRACT

The present disclosure presents a method and an apparatus for reducing cyclic redundancy check (CRC) false detections at a user equipment (UE). For example, the method may include receiving a data packet at the UE, determining whether a state metric value for each of a plurality of vector elements of a last path metric vector of the data packet is less than or equal to a first threshold, incrementing a counter when the state metric value of a vector element of the plurality of vector elements is less than or equal to the first threshold, determining whether the counter is lower than a second threshold, and providing the data packet to an upper layer protocol entity of the UE when a CRC pass for the data packet is determined and the counter is lower than the second threshold. As such, reduced CRC false detections at a UE may be achieved.

CLAIM OF PRIORITY

The present application for patent claims priority to U.S. ProvisionalPatent Application No. 62/029,950, filed Jul. 28, 2014, entitled “CyclicRedundancy Check False Detection Reduction in Communication Systems,”which is assigned to the assignee hereof, and hereby expresslyincorporated by reference herein.

BACKGROUND

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to cyclic redundancy check(CRC) false detection reduction in communication systems.

Wireless communication networks are widely deployed to provide variouscommunication services such as telephony, video, data, messaging,broadcasts, and so on. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources. One example of such a network is the UMTSTerrestrial Radio Access Network (UTRAN). The UTRAN is the radio accessnetwork (RAN) defined as a part of the Universal MobileTelecommunications System (UMTS), a third generation (3G) mobile phonetechnology supported by the 3rd Generation Partnership Project (3GPP).The UMTS, which is the successor to Global System for MobileCommunications (GSM) technologies, currently supports various airinterface standards, such as Wideband-Code Division Multiple Access(W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), andTime Division-Synchronous Code Division Multiple Access (TD-SCDMA). TheUMTS also supports enhanced 3G data communications protocols, such asHigh Speed Packet Access (HSPA), which provides higher data transferspeeds and capacity to associated UMTS networks.

In some wireless communication networks, inefficient and/or ineffectiveutilization of available communication resources, particularly relatedto error detection, may lead to degradations in wireless communication.Even more, the foregoing inefficient resource utilization inhibits userequipments and/or wireless devices from achieving higher wirelesscommunication quality.

For example, W-CDMA systems provide data services using transmissionlinks and associated protocols. At a receiving entity (e.g., a userequipment) in a W-CDMA system, the channel format of a block of datasent by a transmitting entity (e.g., a base station) has to be correctlyidentified and the overhead and payload in the data have to be correctlydecoded to enable proper operation of the system. Some coding schemesare described in detail in 3GPP Standard Technical Specification (TS)25.102. An example coding scheme for the receiving entity is blindtransport format detection (BTFD) for detecting the format of transportchannels, and, in particular, for detecting an end of a block of datafor a channel. This is based on the information that the block may beterminated by an error detection code, e.g., a cyclic redundancy check(CRC) code. The BTFD mechanism uses the information that the block isterminated by a CRC code to determine whether a given sequence of bitsis a CRC code for a block of data (bits) preceding the CRC code (bits).For example, explicit BTFD may involve performing recursive Viterbidecoding followed by CRC checks. When a CRC pass is detected, statevariables are updated and the resulting decoded bits are passed to theupper protocol layers. However, in some instances, the recursivedecoding may result in a false CRC pass where the detected transportformat was not actually transmitted.

For example, CRC bits may help ensure that a receiving entity decodes agrant message correctly when the grant message was actually sent by thetransmitting entity. However, this may not be enough to stop thereceiving entity from falsely detecting a grant message when no grantmessage was sent by the transmitting entity or another type of messagewas sent by the transmitting entity. The receiving entity, in somecases, may decode bits that may match valid CRC bits, resulting in thereceiving entity detecting a false grant message, referred to as “ghostgrants.” The upper protocol layers of the receiving entity may treat theghost grants as a valid grant (e.g., genuine or valid packets receivedfrom the physical layer) which may affect performance of the UE and/orthe network, e.g., dropped voice calls. Additionally, as grant messages(e.g., absolute grant messages) indirectly control the uplink (UL) powerlevel, false detection of a grant message negatively affects networkcapacity and/or receiving entity throughputs. For example, a false grantmessage may set the receiving entity transmit power at a level differentfrom the level intended by the transmitting entity, e.g., a serving basestation or cell, and may cause interference with other entities (e.g.,other UEs or cells).

Therefore, there is a need for improved methods of signal detection forreducing the occurrences or probability of false detection of data sentby a transmitting entity.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

The present disclosure presents an example method and apparatus forreducing cyclic redundancy check (CRC) false detections at a userequipment (UE). For example, the present disclosure presents an examplemethod that may include receiving a data packet at the UE, determiningwhether a state metric value for each of a plurality of vector elementsof a last path metric vector of the data packet is less than or equal toa first threshold, incrementing a counter when the state metric value ofa vector element of the plurality of vector elements is less than orequal to the first threshold, wherein the counter is incremented foreach of the plurality of vector elements in which the state metric valueis less than or equal to the first threshold, determining whether thecounter is lower than a second threshold, and providing the data packetto an upper layer protocol entity of the UE when a CRC pass for the datapacket is determined and the counter is lower than the second threshold.

Additionally, the present disclosure presents an example apparatus forreducing cyclic redundancy check (CRC) false detections that may includemeans for receiving a data packet at the UE, means for determiningwhether a state metric value for each of a plurality of vector elementsof a last path metric vector of the data packet is less than or equal toa first threshold, means for incrementing a counter when the statemetric value of a vector element of the plurality of vector elements isless than or equal to the first threshold, wherein the counter isincremented for each of the plurality of vector elements in which thestate metric value is less than or equal to the first threshold, meansfor determining whether the counter is lower than a second threshold,and means for providing the data packet to an upper layer protocolentity of the UE when a CRC pass for the data packet is determined andthe counter is lower than the second threshold.

In a further aspect, the presents disclosure presents an examplecomputer readable medium storing computer executable code for reducingcyclic redundancy check (CRC) false detections at a user equipment (UE)that may include code for receiving a data packet at the UE, code fordetermining whether a state metric value for each of a plurality ofvector elements of a last path metric vector of the data packet is lessthan or equal to a first threshold, code for incrementing a counter whenthe state metric value of a vector element of the plurality of vectorelements is less than or equal to the first threshold, wherein thecounter is incremented for each of the plurality of vector elements inwhich the state metric value is less than or equal to the firstthreshold, code for determining whether the counter is lower than asecond threshold, and code for providing the data packet to an upperlayer protocol entity of the UE when a CRC pass for the data packet isdetermined and the counter is lower than the second threshold.

Furthermore, in an aspect, the present disclosure presents an examplemobile apparatus to reduce cyclic redundancy check (CRC) falsedetections that may include a receiver configured to receive a datapacket and a processor coupled to a memory, the processor configured todetermine whether a state metric value for each of a plurality of vectorelements of a last path metric vector of the data packet is less than orequal to a first threshold, increment a counter when the state metricvalue of a vector element of the plurality of vector elements is lessthan or equal to the first threshold, wherein the counter is incrementedfor each of the plurality of vector elements in which the state metricvalue is less than or equal to the first threshold, determine whetherthe counter is lower than a second threshold, and provide the datapacket to an upper layer protocol entity of the UE when a CRC pass forthe data packet is determined and the counter is lower than the secondthreshold.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, nature, and advantages of the present disclosure willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout and wherein:

FIG. 1 is a block diagram illustrating an example wireless systemincluding an example user equipment having a reliability determinationcomponent according to aspects of the present disclosure;

FIG. 2 is an example matrix that illustrates distinguishing between areal packet and random noise according to aspects of the presentdisclosure;

FIG. 3 is a flow diagram illustrating aspects of an example method inaspects of the present disclosure;

FIG. 4 is a flowchart illustrating an example aspect of the presentdisclosure;

FIG. 5 is an additional flowchart illustrating an example aspect of thepresent disclosure;

FIG. 6 is a block diagram illustrating aspects of an example userequipment including a reliability determination component according tothe present disclosure;

FIG. 7 is a block diagram conceptually illustrating an example of atelecommunications system including a user equipment with a reliabilitydetermination component according to the present disclosure;

FIG. 8 is a conceptual diagram illustrating an example of an accessnetwork including a user equipment with a reliability determinationcomponent according to the present disclosure;

FIG. 9 is a conceptual diagram illustrating an example of a radioprotocol architecture for the user and control plane that may be used bythe user equipment of the present disclosure;

FIG. 10 is a block diagram conceptually illustrating an example of aNode B in communication with a UE, which includes a reliabilitydetermination component according to the present disclosure, in atelecommunications system in accordance with an aspect of the presentdisclosure; and

FIG. 11 is a block diagram conceptually illustrating an example of aNode B in communication with a UE, which includes a reliabilitydetermination component according to the present disclosure, in atelecommunications system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known components are shown in blockdiagram form in order to avoid obscuring such concepts. In an aspect, asused herein, a component may be one of the parts that make up a system,may be hardware or software, and may be divided into other components.

The present aspects generally relate to reducing a cyclic redundancycheck (CRC) false pass rate for received data in communication systems.Specifically, in some wireless communication systems, CRC may beperformed on each received block of data (or data packet) based on CRCinformation included within the packet. The data packet may be receivedat the UE (e.g., a physical layer of the UE). Although CRC provides areliable indication as to the integrity of a data packet, CRC maynonetheless mistakenly indicate a defective packet (e.g., a data blockcontaining noise or a wrong code word) as valid (e.g., a CRC pass). Insuch cases, providing such defective packets to the upper protocollayers (e.g., medium access control (MAC) layer) may result indegradation in wireless communication quality. For example, a voice callmay be dropped or disrupted due to these defective packets passingthrough the upper protocol layers. Additionally, one or more of a powerlevel at a user equipment (UE), or a network capacity, or a UEthroughput may be negatively affected by the defective packets, whichmay cause a change in a setting or configuration of the UE or thenetwork that affect such metrics. As such, the present aspects provide adetermination as to a reliability or integrity of the data packet, priorto or in addition to CRC processing.

The present method and apparatus provides an efficient and effectivesolution to reduce CRC false detection. In an aspect, the presentdisclosure presents a method and an apparatus for generating areliability metric of a last path metric vector generated by a Viterbialgorithm when the decoding scheme at a receiving entity, such as a userequipment, includes a Viterbi decoder followed by CRC component (e.g.,CRC component). As will be explained in more detail below, the presentaspects use the presence of tail bits at the end of a packet todistinguish between a valid packet (e.g., signal) and random noise. Forinstance, in one use case, a valid packet may contain a known numbertail bits of zero, whereas random noise may not include the known numberof tail bits of zero. As such, according to the Viterbi algorithm, onceall of the known number of tail bits are processed, it is expected thatstate 0 of the last path metric vector output by the Viterbi decodershould have the best (e.g., lowest) state metric value, or should beamong the best, whereas if random noise were received then any state inthe last path metric vector may have the best value. In other words, theknown number of tail bits essentially flush the Viterbi decoder andreturn it to an initial state, so the closer the Viterbi decoder is toprocessing all of the tail bits, the closer the state 0 should be toapproaching the lower state metric value. Based on this principle, thepresent aspects can process a received data packet having an unknownformat and compare a state metric value of state 0 to a threshold anddetermine if state 0 is among the best (e.g., lowest) state metricvalues, e.g., one of a threshold number of states having the best (e.g.,lowest) state metric values. This may be referred to as a State 0 AmongFinalists methodology. As such, based on whether or not the state 0state metric value is among the best, the present aspects generate areliability metric (e.g., indicating good or bad reliability) that maybe used to distinguish between correct and false (incorrect) detectionsof valid data packets, thereby reducing the probability of CRC falsedetections. In some cases, the present aspects may also have anegligible impact on missed detection performance, e.g., a decision of“invalid CRC pass” when a valid data packet is present.

In particular, the output of a Viterbi decoder may be represented in adiagram, e.g., a Trellis graph, having rows representing the possibleencoder states and columns representing each time instant in a decodeddata packet, with lines that define paths connecting state transitionsfrom one time instant to another and state metrics that define anaccumulated error between the states at the previous time instance andthe states at the current time instance. For example, for a Viterbidecoder having 256 states and for a data packet having 60 data bits, theTrellis graph would have 256 rows and 60 columns, and state 0 would havea state metric value of 0 at an initial time instance and also a valueof 0 or another value that is among the best values at a last timeinstance, e.g., the last path metric, when a valid data packet isreceived. As such, for a Trellis graph, each column of values may beconsidered as a vector and the numbers in the vector, referred to asvector elements or elements, represent path metrics (or path metricvalues) which is a total distance from state 0 (e.g., source node) tothe node. A state metric value may be defined as a value of totaldistance up to the present state. The last metric vector is the rightmost column in the matrix.

Specifically, the present method and apparatus may receive a path metricvector (e.g., a last path metric vector), also referred to as a statemetric vector (e.g., a last state metric vector), from a Viterbi decoderand, based on existence of known tail bits at the end of a data packet,distinguish between a valid data packet and noise. In particular, thelast path metric vector may be associated with a data packet and mayinclude a plurality of vector elements corresponding to a plurality ofencoder states of the Viterbi decoder.

To make the distinction between a valid packet and random noise (e.g.,thermal noise), the present method and apparatus may perform a State 0Among Finalists analysis. For instance, the present method and apparatusmay use a reliability metric based on the knowledge that some tail bitsare added to a proper code block (e.g., proper packet) which will make afinal path metric vector to be biased in a way that state 0 may be thebest or among the best by determining whether a state metric (“SM”)value for each of the plurality of vector elements is less than or equalto a first threshold value, where the first threshold value may beadjustably configured to a level that indicates a reliability. Thepresent aspects may determine an order or index of a first element(e.g., SM[0]) in a sorted vector (e.g., sorted from lowest SM value tohighest SM value) and compare the first element with the first thresholdvalue. In addition, the present method and apparatus may increment acounter value when the state metric value of a vector element of theplurality of vector elements is less than or equal to the firstthreshold value. Moreover, the present method and apparatus maydetermine whether the counter value equals or exceeds a second thresholdvalue. Further, the present aspects may decrease the second thresholdvalue when the data packet has passed the CRC test. The present methodand apparatus may also provide the data packet to an upper layerprotocol entity (e.g., MAC layer) when a CRC pass for the data packet isdetermined and the counter value does not meet or exceed a secondthreshold value. Accordingly, the present method and apparatus providereduced CRC false detection and/or have a minor impact on the misseddetection performance.

Referring to FIG. 1, in an aspect, a communications system 100 isillustrated that includes a user equipment (UE) 102, a Viterbi decoder110, a CRC component 120, a reliability determination component 130,and/or an AND gate 140 for CRC false detection reduction (e.g., forreducing CRC “false pass” occurrences) in the communications system. Forexample, a CRC false pass may occur when CRC component 120 outputs a“valid CRC pass” decision when signal is absent (e.g., no signal istransmitted by the transmitting entity). In an aspect, output of CRCcomponent 120 and output of reliability determination component 130 areconnected via an AND gate 140 so that a CRC pass is declared only whenCRC component 120 outputs a pass and the reliability determinationcomponent 130 outputs a reliability metric value of “GOOD” for reducingCRC false detection reduction at the UE as described below in detail.

FIG. 2 is an example matrix that illustrates distinguishing between areal packet and random noise according to aspects of the presentdisclosure.

In an example aspect, a 256×40 matrix is generated for a symbol that isreceived at UE 102 (e.g., at receiver of UE 102). The 256×40 matrix 202includes values for the 256 states (e.g., state metric values)represented by the values in the columns which may be an accumulateddistance from a source node. The values in the last column may be sortedfor identifying the minimum values which may correspond to state zero.In an aspect, if the receiver received a real packet (i.e., not randomnoise), the value of state zero will be the minimum value or at leastone of the minimum values. In an additional or optional aspect, if thereceiver received random noise (i.e., transmitter did not transmitanything), any element in the last column (e.g., 40^(th) column) may bethe minimum value or one of the minimum values.

However, a UE's receiver does not have any knowledge of the size of thepacket transmitted from the transmitter. For example, a receiver of UE102 does not have any knowledge of whether the packet is 40, 60, or 80bits long. In an aspect, for example, after time unit 40 (212), statemetric values may be calculated for the various states and thecalculated state metric values are sorted and compared with state metricvalue of state zero. For instance, in an aspect, if there are states(e.g., 15 elements) with state metric values less than the value ofstate zero, then calculating of state metric values continues till thenext optional block, e.g., time unit 60 (214). The order of state zeromay be called as the reliability metric. The process of calculatingstate metric values, sorting the calculated state metric values, andcomparing state metric values with state zero are repeated, and thereliability metrics are calculated. If the reliability metric at timeunit 60 is better than the reliability metric at time unit 40, thereliability metric at time unit 40 is discarded (if CRC passes), and soon.

Referring to FIG. 3, in an aspect, a wireless communication system 300includes UE 102 in communication coverage of base station 314. UE 102may communicate with network entity 316 via base station 314. In someaspects, multiple UEs, including UE 102, may be in communicationcoverage with one or more base stations, including base station 314. Inan example, UE 102 may transmit and/or receive wireless communicationsto and/or from base station 314 via one or more communication channels318, and may include a receiver 360 and a display 370. Such wirelesscommunications may include, but are not limited to, one or more datapackets.

In an aspect, UE 102 may also be referred to by those skilled in the art(as well as interchangeably herein) as a mobile station, a subscriberstation, a mobile unit, a subscriber unit, a wireless unit, a remoteunit, a mobile device, a wireless device, a wireless communicationsdevice, a remote device, a mobile subscriber station, an accessterminal, a mobile terminal, a wireless terminal, a remote terminal, ahandset, a terminal, a user agent, a mobile client, a client, a devicefor the Internet-of-Things, or some other suitable terminology.Additionally, base station 314 may be a macrocell, small cell, picocell,femtocell, relay, Node B, mobile Node B, UE (e.g., communicating inpeer-to-peer or ad-hoc mode with UE 102), or substantially any type ofcomponent that can communicate with UE 102 to provide wireless networkaccess at the UE 102.

According to the present aspects, UE 102 may include reliabilitydetermination component 130, which may be configured to reduce CRC falsedetections, e.g., a decision of “valid CRC pass” when a valid datapacket is not actually transmitted by the transmitting entity (e.g.,base station 314). For example, reliability determination component 130may be configured to determine reliability of a data packet from anoutput of a Viterbi decoder 110 prior to (e.g., without considering) CRCdetermination by CRC component 120. In some aspects, CRC component 120may execute a class of linear error detecting codes which generateparity check bits by finding the remainder of a polynomial division. Theoutput of CRC component 120 may be, for example, a decision of a “validCRC pass” or “pass” when a signal (e.g., data packet) is present or adecision of “invalid CRC pass” or “false pass” when a signal is notpresent (e.g., may be noise). However, CRC component 120 may incorrectlyoutput a “valid CRC pass” or “pass” decision when a signal is notpresent.

In an aspect, upon receiving communication (e.g., signal) in the formof, for example, one or more data packets, from base station 314,communications component 350 may provide the one or more data packets toViterbi decoder 110. In an aspect, UE 102 may include a receiver 360 forreceiving and decoding RF signals. The receiver 360 may includehardware, firmware, and/or software code executable by a processor forreceiving data. The receiver 360 may be, for example, a radio frequency(RF) receiver. In an aspect, the receiver 360 may receive and decodesignals transmitted by base station 314 and/or network entity 316. In anadditional or optional aspect, receiver 360 may be included in atransceiver at UE 102. Viterbi decoder 110 may utilize a Viterbidecoding procedure in decoding a stream of data (e.g., bits) associatedwith the one or more data packets that have been encoded using, forinstance, a convolutional code. In such aspects, a Viterbi procedure maybe a dynamic programming procedure for locating a most likely sequenceof a hidden state (e.g., Viterbi path) that results in a sequence ofobserved events. Additionally, a convolutional code may be a type oferror-correcting code in which each m-bit information symbol (each m-bitstring) to be encoded is transformed into an n-bit symbol, where m/n isthe code rate (e.g., with n >m) and the transformation may be a functionof the last k information symbols, where k is the constraint length ofthe code.

In an aspect, UE 102 may include a communication component which mayinclude a bus or other links to enable communication between thecomponents of UE 102 and/or reliability determination component 130 andinterface for communication with external devices or components.Additionally, UE 102 may include a display 370 for visually displayingoutput of the UE 102. For example, display 370 may be a liquid crystaldisplay (LCD).

For example, reliability determination component 130 may use a last pathmetric vector 342 associated with a data packet (e.g., which includes aplurality of vector elements) for decoding. In other aspects, the lastpath metric vector 342 may be associated with random noise (or noise).For instance, in an aspect, reliability determination component 130 mayuse a last path metric vector 342 that may include a number of tailbits, e.g., eight tail bits. The number of tail bits depends on theconfiguration. In such aspects, reliability determination component 130may be configured to identify a valid or reliable data packet as onehaving or otherwise including the tail bits (e.g., eight tail bits) setto zeroes. In an additional or optional aspect, reliabilitydetermination component 130 may be configured to identify an invalid orunreliable data packet (e.g., random noise) as one without the tailbits. That is, the last path metric vector 342 may be associated with aproper data packet if the tail bits are set to zeroes while in otheraspects the last path metric vector is associated with random noisesymbols the tail bets are absent. In an additional aspect, reliabilitydetermination component 130 may be configured to identify a valid orreliable data packet based on the number of vector elements in the lastpath metric vector with a sate metric value lower than or equal to thestate metric value of state zero (e.g., SM[0]).

Further, reliability determination component 130 may be configured todetermine whether state metric value 332 for each of the number ofvector elements in the last path metric vector is less than or equal toa first threshold 334. In an aspect, the first threshold 334 may be setto a value which is equal to state metric value of state zero. Forexample, reliability determination component 130 may be configured todetermine whether state metric value 332 associated with a vectorelement is less than or equal to the first threshold 334. Accordingly,reliability determination component 130 may be configured to incrementcounter 336 when the state metric value 332 of a vector element is lessthan or equal to the first threshold 334. However, reliabilitydetermination component 130 may be configured to skip incrementingcounter 236 and proceed to comparing the state metric value 332 of asubsequent vector element with state metric value of state zero whenstate metric value 332 for the previous vector element is not less thanor equal to (e.g., greater than) the first threshold 334.

For example, in an aspect, reliability determination component 130 maybe configured to increment counter 336 when a state metric value for avector element is less than or equal to the state metric value of statezero, e.g., SM[0]. However, reliability determination component 130 maybe configured to skip incrementing counter 336 and proceed to comparingthe state metric value of a subsequent vector element when the statemetric value of the previous vector element is greater than the statemetric value of state zero, SM[0].

In addition, reliability determination component 130 may be configuredto provide an indication as to the reliability of the data packet bydetermining whether counter 336 equals or exceeds a second threshold338. In some aspects, the second threshold 338 may be alternativelyreferred to as N_(finalists), where the value of N_(finalists) may bethe highest number of vector elements in last path metric vector 342.Further, CRC component 120 may be configured to perform a CRC procedureon or using the data packet to output or provide a CRC reliabilityindication (e.g., CRC pass or CRC fail). In an aspect, reliabilitydetermination component 130 may be configured to provide the data packetto an upper layer protocol entity when CRC component 120 determines aCRC pass for the data packet and the counter 336 does not meet or exceedsecond threshold 338.

In some non-limiting aspects, the second threshold 338 is initially setto a value of 256 (e.g., 8 tail bits with 256 states) or any userdefined value according to the application associated with the packetdata being received and/or the required balance between CRC misseddetections (e.g., false negatives) and false passes. A CRC misseddetection may be defined as CRC component 120 outputting a decision of“Invalid CRC pass” when signal is present. Further, the second threshold338 may be configurable based on one or more of results of thereliability determination component 130 and CRC component 120. Forinstance, reliability determination component 130 may be configured todecrease second threshold 338 when counter 336 is less than or equal tosecond threshold 338, and in some aspects, when the CRC passed. In anaspect, the decreasing of second threshold 338 may be repeated for atransport format (e.g., in BTFD) that achieves a CRC pass with lowervalue from reliability determination component 130. The lowest value forsecond threshold 338 may be 0. That is, value of state 0 (e.g., SM[0])is the minimal value among the last metric vector in the Viterbidecoder. In a further additional or optional aspect, second threshold338 may be reset (e.g., to a value of 256) for a new packet received atthe UE (e.g., at the physical layer of the UE).

Moreover, in an alternative or additional aspect, UE 102 may includecommunications component 350 configured to facilitate or otherwiseenable UE 102 to communicate with base station via one or morecommunication channels according to or utilizing one or more RATs. Insuch aspects, the one or more communication channels 318 may enablecommunication on both the uplink and downlink between UE 102 and basestation 314.

For example, in a non-limiting aspect, when decoding is performed onW-CDMA R99 voice channels using blind transport format detection (BTFD)configuration, second threshold 338 may be initially set to a value of356, and each transport format (e.g., each determination that the statemetric value is less than or equal to the first threshold value) thatpasses the CRC (e.g., CRC pass indication) may decrease the secondthreshold 338. Further, when decoding is performed on random noise(e.g., tail bits are absent), the probability of having state 0 amongthe final four i.e., N_(f)=4) is

$\frac{4}{256}$since every state can have the ideal state metric with equalprobability. Such an aspect would result in a reduction of theprobability of false pass rate by a factor of

$\frac{4}{256} - {\frac{1}{64}.}$This tactor of reduction may be multiplied by the probability for CRCfalse pass represented as 2^(−CRCLength). As such, the final probabilityfor CRC false pass may be:

$P_{{False}\mspace{14mu}{pass}} = {\frac{1}{2^{CRCLength}} \cdot \frac{N_{f}}{N_{states}}}$

Referring to FIG. 3, the methods are shown and described as a series ofacts for purposes of simplicity of explanation. However, it is to beunderstood and appreciated that the methods (and further methods relatedthereto) are not limited by the order of acts, as some acts may, inaccordance with one or more aspects, occur in different orders and/orconcurrently with other acts from that shown and described herein. Forexample, it is to be appreciated that the methods may alternatively berepresented as a series of interrelated states or events, such as in astate diagram. Moreover, not all illustrated acts may be required toimplement a method in accordance with one or more features describedherein.

FIG. 4 illustrates an example methodology 400 for cyclic redundancycheck (CRC) false detection reduction at a user equipment (UE).

In an aspect, at block 410, methodology 400 may include receiving a datapacket at the UE. For example, in an aspect, UE 102 and/or reliabilitydetermination component 130 may include a specially programmed processormodule, or a processor executing specially programmed code stored in amemory, to receive a data packet at the UE (e.g., physical layer 1007 ofFIG. 7). In an aspect, reliability determination component 130 mayinclude a receiving component 352 to perform this functionality.

In an aspect, at block 420, methodology 400 may include determiningwhether a state metric value for each of a plurality of vector elementsof a last path metric vector of the data packet is less than or equal toa first threshold. For example, in an aspect, UE 102 and/or reliabilitydetermination component 130 may include a specially programmed processormodule, or a processor executing specially programmed code stored in amemory, to determine determining whether a state metric value for eachof a plurality of vector elements of a last path metric vector of thedata packet is less than or equal to a first threshold. For example, asdescribed herein, UE 102 (FIG. 1) may execute reliability determinationcomponent 130 (FIG. 1) to determine whether a state metric value 332(FIG. 3) for each of a plurality of vector elements of a last pathmetric of the data packet is less than or equal to a first threshold 334(FIG. 3). In an aspect, reliability determination component may includea state metric value determining component 354 to perform thisfunctionality.

In an aspect, at block 430, methodology 400 may include incrementing acounter when the state metric value of a vector element of the pluralityof vector elements is less than or equal to the first threshold, whereinthe counter is incremented for each of the plurality of vector elementsin which the state metric value is less than or equal to the firstthreshold. For example, in an aspect, UE 102 and/or reliabilitydetermination component 130 may include a specially programmed processormodule, or a processor executing specially programmed code stored in amemory, to increment a counter when the state metric value of a vectorelement of the plurality of vector elements is less than or equal to thefirst threshold, wherein the counter is incremented for each of theplurality of vector elements in which the state metric value is lessthan or equal to the first threshold. For example, as described herein,UE 102 (FIG. 1) may execute reliability determination component 130(FIG. 1) to increment counter 336 (FIG. 3) when the state metric value332 (FIG. 3) of a vector element is less than or equal to firstthreshold 334 (FIG. 3). In an additional aspect, the counter 336 isincremented for each of the plurality of vector elements in which thestate metric value is less than or equal to the first threshold, thatis, once every time the state metric value of a vector elementassociated with the data packet is less than or equal to the firstthreshold 334. In an aspect, reliability determination component mayinclude a counter incrementing component 356 to perform thisfunctionality.

In an aspect, at block 440, methodology 400 may include determiningwhether the counter is lower than a second threshold. For example, in anaspect, UE 102 and/or reliability determination component 130 mayinclude a specially programmed processor module, or a processorexecuting specially programmed code stored in a memory, to determiningwhether the counter is lower than a second threshold. For example, asdescribed herein, UE 102 (FIG. 1) may execute reliability determinationcomponent 130 (FIG. 1) to determine whether counter 336 (FIG. 3) islower than second threshold 338 (FIG. 3). In an aspect, reliabilitydetermination component may include counter comparing component 358 toperform this functionality.

In an aspect, at block 450, methodology 400 may include providing thedata packet to an upper layer protocol entity of the UE when a CRC passfor the data packet is determined and the counter is lower than thesecond threshold. For example, in an aspect, UE 102 and/or reliabilitydetermination component 130 may include a specially programmed processormodule, or a processor executing specially programmed code stored in amemory, to provide the data packet to an upper layer protocol entity ofthe UE (e.g., MAC layer 1009 of FIG. 9) when a CRC pass for the datapacket is determined and the counter is lower than the second threshold.For example, as described herein, UE 102 (FIG. 1) may executereliability determination component 130 (FIG. 1) to provide the datapacket to an upper layer protocol entity of the UE when a CRC pass forthe data packet is determined and counter 336 (FIG. 3) is lower thansecond threshold 338 (FIG. 3). In an aspect, reliability determinationcomponent may include a packet transmission component 362 to performthis functionality.

Referring to FIG. 5, in an aspect, UE 102 and/or reliabilitydetermination component 130 (of FIG. 1) may perform an aspect of amethod 500 for reducing CRC false detection.

In an aspect, at block 502, method 500 may initialize k to a value of 1(e.g., k=1 and count (cnt) to a value of zero (e.g., (cnt)=0). Forinstance, the variable k may be the index for which the state metricvalue is compared to the state metric value of state zero. The cntvariable may be the same or similar as counter 336 (FIG. 3). At block504, method 500 may determine whether the state metric value of index k(e.g., SM[k]) is less than or equal to the state metric value of indexof zero (e.g., SM[0]), which may be the same as or similar to firstthreshold 334 (FIG. 3). Method 500 may proceed to block 505 when thedetermination at block 504 is in the affirmative and cnt is incremented(e.g., by 1). Otherwise, method 500 may proceed to block 506 where k isincremented (e.g., such that next vector element in the vector isconsidered for comparing with state metric value of zero).

At block 508, method 500 may determine whether k is equal to N_(states)(e.g., the number of states indicating that all the vector elements inthe last past metric vector were compared). Method 500 may return toblock 504 when k is less than N_(states). That is, not all the vectorelements were compared and additional vector elements are remaining forcomparison. Otherwise, method 500 may proceed to block 510 to determinewhether cnt is less than N_(finalists), which may be the same as orsimilar to second threshold 338 (FIG. 3). Method 500 may proceed toblock 512 and indicate the data packet as reliable or “GOOD” packet whencnt is less than N_(finalists). Otherwise, method 500 may proceed toblock 514 and indicate the data packet as not reliable or “BAD” packetwhen cnt is not less than the N_(finalists). In an additional aspect,reliability determination component 130 may perform the steps orfunctions described above at blocks 502, 504, 505, 506, 508, 510, 512,and/or 514.

Referring to FIG. 6, in an aspect, a UE such as UE 102 (FIG. 1) mayperform one aspect of a method 600 for reducing CRC false detection.Method 600 may be performed or executed by UE 102 (FIG. 1) and/or anyone or more of the components and/or subcomponents of UE 102 (FIG. 1)(e.g., reliability determination component 130, FIG. 1). It should beunderstood that any one or more of the reliability determinationcomponent 130, Viterbi decoder 110, CRC component 120 and/orcommunications component 350 may be configured to execute all or aportion of method 500.

At block 602, method 600 may initialize or otherwise receive thetransport format index (TF_idx) at value zero (e.g., index zero).Additionally, at block 604, method 600 may initialize or otherwise setN_(finalists) threshold value (e.g., alternatively referred to as secondthreshold 338, FIG. 3) to a value of “D.” Further, at block 606, method600 may set the state metric value (SM) to a value equal to an output ofthe Viterbi decoder having input index of TF-idx. At block 608, method600 may determine reliability of the state metric value by comparing thestate metric value to N_(finalists). In some aspects, any one ofmethodology 400 (FIG. 4) and 500 (FIG. 5) may be implemented as part ofblock 608.

The output or decision may be received at block 610, where adetermination is made on whether the output is reliable. Method 600 mayproceed to block 620 when a determination of an unreliable state metricvalue is made at block 610. Otherwise, method 600 may proceed to block612, where output bits (outBits) from Viterbi traceback procedure areobtained. Further, at block 614, the outBits from block 612 are thenchecked or verified using a CRC procedure. At block 616, a determinationmay be made whether the CRC procedure resulted in a pass for the outBits(e.g., corresponding to the state metric).

Method 600 may proceed to block 620 when a failure or no pass isdetermined at block 616. Otherwise, method 600 may proceed to block 618when a CRC pass is determined at block 616. Specifically, at block 618,the N_(finalists) threshold value may be set to a counter value.Further, at block 620, method 600 may determine whether a last transportformat (TF) has been reached. If not, method 600 may proceed to block622 to increment the transport format and proceed back to block 84.Otherwise, method 600 may proceed to block 624, where the method mayend.

As illustrated in FIG. 7, UE 102 may include a processor 702, memory704, communications component 706, data store 708, user interface 710,receiver 360, display 370, and/or reliability determination component130. Reliability determination component 130 may be implementedpartially or fully in a specially programmed or configured computerdevice to perform the functions described herein. Further, in animplementation, UE 102 may include reliability determination component130 and its sub-components, including receiving component 352, statemetric value determining component 354, counter incrementing component356, counter comparing component 358, and/or packet transmissioncomponent 362, in specially programmed computer readable instructions orcode, firmware, hardware, or some combination thereof.

In an aspect, for example as represented by the dashed lines,reliability determination component 130 may be implemented in orexecuted using one or any combination of processor 702, memory 704,communications component 706, and data store 708. For example,reliability determination component 130 may be defined or otherwiseprogrammed as one or more processor modules of processor 702. Further,for example, reliability determination component 130 may be defined as acomputer-readable readable medium stored in memory 704 and/or data store708 and executed by processor 702. Moreover, for example, inputs andoutputs relating to operations of reliability determination component130 may be provided or supported by communications component 706, whichmay provide a bus between the components of computer device 700 or aninterface for communication with external devices or components.

UE 102 may include processor 702 specially configured to carry outprocessing functions associated with one or more of components andfunctions described herein. Processor 702 can include a single ormultiple set of processors or multi-core processors. Moreover, processor702 can be implemented as an integrated processing system and/or adistributed processing system.

User equipment 102 further includes memory 704, such as for storing dataused herein and/or local versions of applications and/or instructions orcode being executed by processor 702, such as to perform the respectivefunctions of the respective entities described herein. Memory 704 caninclude any type of memory usable by a computer, such as random accessmemory (RAM), read only memory (ROM), tapes, magnetic discs, opticaldiscs, volatile memory, non-volatile memory, and any combinationthereof.

Further, user equipment 102 includes communications component 706 (e.g.,same as or similar to communications component 350) that provides forestablishing and maintaining communications with one or more partiesutilizing hardware, software, and services as described herein.Communications component 706 may carry communications between componentson user equipment 102, as well as between user and external devices,such as devices located across a communications network and/or devicesserially or locally connected to user equipment 102. For example,communications component 706 may include one or more buses operable forinterfacing with external devices.

Additionally, user equipment 102 may further include data store 708,which can be any suitable combination of hardware and/or software, thatprovides for mass storage of information, databases, and programsemployed in connection with aspects described herein. For example, datastore 708 may be a data repository for applications not currently beingexecuted by processor 702.

User equipment 102 may additionally include a user interface 710operable to receive inputs from a user of user equipment 102, andfurther operable to generate outputs for presentation to the user. Userinterface 710 may include one or more input devices, including but notlimited to a keyboard, a number pad, a mouse, a touch-sensitive display(e.g., display 370), a navigation key, a function key, a microphone, avoice recognition component, any other mechanism capable of receiving aninput from a user, or any combination thereof. Further, user interface710 may include one or more output devices, including but not limited toa display (e.g., display 370), a speaker, a haptic feedback mechanism, aprinter, any other mechanism capable of presenting an output to a user,or any combination thereof. Additionally, UE 102 may include receiver360 for receiving and decoding RF signals, which may be included in atransceiver at the UE.

The various concepts presented throughout this disclosure may beimplemented across a broad variety of telecommunication systems, networkarchitectures, and communication standards.

By way of example and without limitation, the aspects of the presentdisclosure illustrated in FIG. 8 are presented with reference to a UMTSsystem 800 employing a W-CDMA air interface. A UMTS network includesthree interacting domains: a Core Network (CN) 804, a UMTS TerrestrialRadio Access Network (UTRAN) 802, and User Equipment (UE) 810 that maybe the same as or similar to UE 102 including reliability determinationcomponent 130 (FIG. 1). In this example, the UTRAN 802 provides variouswireless services including telephony, video, data, messaging,broadcasts, and/or other services. The UTRAN 802 may include a pluralityof Radio Network Subsystems (RNSs) such as an RNS 807, each controlledby a respective Radio Network Controller (RNC) such as an RNC 206. Here,the UTRAN 802 may include any number of RNCs 206 and RNSs 807 inaddition to the RNCs 806 and RNSs 807 illustrated herein. The RNC 206 isan apparatus responsible for, among other things, assigning,reconfiguring and releasing radio resources within the RNS 807. The RNC206 may be interconnected to other RNCs (not shown) in the UTRAN 802through various types of interfaces such as a direct physicalconnection, a virtual network, or the like, using any suitable transportnetwork.

Communication between a UE 810 and a Node B 808 may be considered asincluding a physical (PHY) layer and a medium access control (MAC)layer. Further, communication between a UE 810 and an RNC 806 by way ofa respective Node B 808 may be considered as including a radio resourcecontrol (RRC) layer. In the instant specification, the PHY layer may beconsidered layer 1; the MAC layer may be considered layer 2; and the RRClayer may be considered layer 3. Information herein below utilizesterminology introduced in the RRC Protocol Specification, 3GPP TS 25.331v9.1.0, incorporated herein by reference.

The geographic region covered by the RNS 807 may be divided into anumber of cells, with a radio transceiver apparatus serving each cell. Aradio transceiver apparatus is commonly referred to as a Node B in UMTSapplications, but may also be referred to by those skilled in the art asa base station (BS), a base transceiver station (BTS), a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), an access point (AP), or someother suitable terminology. For clarity, three Node Bs 808 are shown ineach RNS 807; however, the RNSs 807 may include any number of wirelessNode Bs. The Node Bs 808 provides wireless access points to a CN 204 forany number of mobile apparatuses.

Examples of a mobile apparatus include a cellular phone, a smart phone,a session initiation protocol (SIP) phone, a laptop, a notebook, anetbook, a smartbook, a personal digital assistant (PDA), a satelliteradio, a global positioning system (GPS) device, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, or any other similar functioning device. The mobileapparatus is commonly referred to as a UE in UMTS applications, but mayalso be referred to by those skilled in the art as a mobile station, asubscriber station, a mobile unit, a subscriber unit, a wireless unit, aremote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a terminal, a user agent, a mobile client, aclient, or some other suitable terminology. For illustrative purposes,one UE 810 is shown in communication with a number of the Node Bs 808.The DL, also called the forward link, refers to the communication linkfrom a Node B 808 to a UE 810, and the UL, also called the reverse link,refers to the communication link from a UE 810 to a Node B 808.

The CN 804 interfaces with one or more access networks, such as theUTRAN 802. As shown, the CN 804 is a GSM core network. However, as thoseskilled in the art will recognize, the various concepts presentedthroughout this disclosure may be implemented in a RAN, or othersuitable access network, to provide UEs with access to types of CNsother than GSM networks.

The CN 804 includes a circuit-switched (CS) domain and a packet-switched(PS) domain. Some of the circuit-switched elements are a Mobile servicesSwitching Centre (MSC), a Visitor location register (VLR) and a GatewayMSC. Packet-switched elements include a Serving GPRS Support Node (SGSN)and a Gateway GPRS Support Node (GGSN). Some network elements, like EIR,HLR, VLR and AuC may be shared by both of the circuit-switched andpacket-switched domains. In the illustrated example, the CN 804 supportscircuit-switched services with a MSC 812 and a GMSC 814. In someapplications, the GMSC 814 may be referred to as a media gateway (MGW).One or more RNCs, such as the RNC 806, may be connected to the MSC 812.The MSC 812 is an apparatus that controls call setup, call routing, andUE mobility functions.

The MSC 812 also includes a VLR that contains subscriber-relatedinformation for the duration that a UE is in the coverage area of theUTRAN 802. The GMSC 814 provides a gateway through the MSC 812 for theUE to access a circuit-switched network 816. The GMSC 814 includes ahome location register (HLR) 815 containing subscriber data, such as thedata reflecting the details of the services to which a particular userhas subscribed. The HLR is also associated with an authentication center(AuC) that contains subscriber-specific authentication data. When a callis received for a particular UE, the GMSC 814 queries the HLR 815 todetermine the UE's location and forwards the call to the particular MSCserving that location.

The CN 804 also supports packet-data services with a serving GPRSsupport node (SGSN) 818 and a gateway GPRS support node (GGSN) 820.GPRS, which stands for General Packet Radio Service, is designed toprovide packet-data services at speeds higher than those available withstandard circuit-switched data services. The GGSN 820 provides aconnection for the UTRAN 802 to a packet-based network 822. Thepacket-based network 822 may be the Internet, a private data network, orsome other suitable packet-based network. The primary function of theGGSN 820 is to provide the UEs 810 with packet-based networkconnectivity. Data packets may be transferred between the GGSN 820 andthe UEs 810 through the SGSN 818, which performs primarily the samefunctions in the packet-based domain as the MSC 812 performs in thecircuit-switched domain.

An air interface for UMTS may utilize a spread spectrum Direct-SequenceCode Division Multiple Access (DS-CDMA) system. The spread spectrumDS-CDMA spreads user data through multiplication by a sequence ofpseudorandom bits called chips. The “wideband” W-CDMA air interface forUMTS is based on such direct sequence spread spectrum technology andadditionally calls for a frequency division duplexing (FDD). FDD uses adifferent carrier frequency for the UL and DL between a Node B 808 and aUE 810. Another air interface for UMTS that utilizes DS-CDMA, and usestime division duplexing (TDD), is the TD-SCDMA air interface. Thoseskilled in the art will recognize that although various examplesdescribed herein may refer to a W-CDMA air interface, the underlyingprinciples may be equally applicable to a TD-SCDMA air interface.

An HSPA air interface includes a series of enhancements to the 3G/W-CDMAair interface, facilitating greater throughput and reduced latency.Among other modifications over prior releases, HSPA utilizes hybridautomatic repeat request (HARQ), shared channel transmission, andadaptive modulation and coding. The standards that define HSPA includeHSDPA (high speed downlink packet access) and HSUPA (high speed uplinkpacket access, also referred to as enhanced uplink, or EUL).

HSDPA utilizes as its transport channel the high-speed downlink sharedchannel (HS-DSCH). The HS-DSCH is implemented by three physicalchannels: the high-speed physical downlink shared channel (HS-PDSCH),the high-speed shared control channel (HS-SCCH), and the high-speeddedicated physical control channel (HS-DPCCH).

Among these physical channels, the HS-DPCCH carries the HARQ ACK/NACKsignaling on the uplink to indicate whether a corresponding packettransmission was decoded successfully. That is, with respect to thedownlink, the UE 810 provides feedback to the node B 808 over theHS-DPCCH to indicate whether it correctly decoded a packet on thedownlink.

HS-DPCCH further includes feedback signaling from the UE 810 to assistthe node B 808 in taking the right decision in terms of modulation andcoding scheme and precoding weight selection, this feedback signalingincluding the CQI and PCI.

“HSPA Evolved” or HSPA+ is an evolution of the HSPA standard thatincludes MIMO and 64-QAM, enabling increased throughput and higherperformance. That is, in an aspect of the disclosure, the node B 808and/or the UE 810 may have multiple antennas supporting MIMO technology.The use of MIMO technology enables the node B 808 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity.

Multiple Input Multiple Output (MIMO) is a term generally used to referto multi-antenna technology, that is, multiple transmit antennas(multiple inputs to the channel) and multiple receive antennas (multipleoutputs from the channel). MIMO systems generally enhance datatransmission performance, enabling diversity gains to reduce multipathfading and increase transmission quality, and spatial multiplexing gainsto increase data throughput.

Spatial multiplexing may be used to transmit different streams of datasimultaneously on the same frequency. The data steams may be transmittedto a single UE 210 to increase the data rate or to multiple UEs 810 toincrease the overall system capacity. This is achieved by spatiallyprecoding each data stream and then transmitting each spatially precodedstream through a different transmit antenna on the downlink. Thespatially precoded data streams arrive at the UE(s) 810 with differentspatial signatures, which enables each of the UE(s) 810 to recover theone or more the data streams destined for that UE 810. On the uplink,each UE 810 may transmit one or more spatially precoded data streams,which enables the node B 808 to identify the source of each spatiallyprecoded data stream.

Spatial multiplexing may be used when channel conditions are good. Whenchannel conditions are less favorable, beamforming may be used to focusthe transmission energy in one or more directions, or to improvetransmission based on characteristics of the channel. This may beachieved by spatially precoding a data stream for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

Generally, for MIMO systems utilizing n transmit antennas, n transportblocks may be transmitted simultaneously over the same carrier utilizingthe same channelization code. Note that the different transport blockssent over the n transmit antennas may have the same or differentmodulation and coding schemes from one another.

On the other hand, Single Input Multiple Output (SIMO) generally refersto a system utilizing a single transmit antenna (a single input to thechannel) and multiple receive antennas (multiple outputs from thechannel). Thus, in a SIMO system, a single transport block is sent overthe respective carrier.

Referring to FIG. 9, an access network 900 in a UTRAN architecture isillustrated, and may include one or more UEs 980, 982, 984, 986, 988,and 990, which may be the same or similar to UE 102 (FIGS. 1 and 3) inthat they are configured to include reliability determination component130 (FIGS. 1 and 3; for example, illustrated here as being associatedwith UE 986) for reducing CRC false detections. The multiple accesswireless communication system includes multiple cellular regions(cells), including cells 902, 904, and 906, each of which may includeone or more sectors. The multiple sectors can be formed by groups ofantennas with each antenna responsible for communication with UEs in aportion of the cell. For example, in cell 902, antenna groups 912, 914,and 916 may each correspond to a different sector. In cell 904, antennagroups 918, 920, and 922 each correspond to a different sector. In cell906, antenna groups 924, 926, and 928 each correspond to a differentsector. The cells 902, 904 and 906 may include several wirelesscommunication devices, e.g., User Equipment or UEs, which may be incommunication with one or more sectors of each cell 902, 904 or 906. Forexample, UEs 980 and 982 may be in communication with Node B 942, UEs984 and 986 may be in communication with Node B 944, and UEs 988 and 940can be in communication with Node B 946. Here, each Node B 942, 944, 946is configured to provide an access point to a CN 804 (see FIG. 8) forall the UEs 980, 982, 984, 986, 988, 990 in the respective cells 902,904, and 906. In an aspect, the UEs 980, 982, 984, 986, 988 and/or 990may include reliability determination component 130 (FIG. 1).

As the UE 984 moves from the illustrated location in cell 904 into cell906, a serving cell change (SCC) or handover may occur in whichcommunication with the UE 984 transitions from the cell 904, which maybe referred to as the source cell, to cell 906, which may be referred toas the target cell. Management of the handover procedure may take placeat the UE 984, at the Node Bs corresponding to the respective cells, ata radio network controller 806 (see FIG. 8), or at another suitable nodein the wireless network. For example, during a call with the source cell904, or at any other time, the UE 984 may monitor various parameters ofthe source cell 904 as well as various parameters of neighboring cellssuch as cells 906 and 902. Further, depending on the quality of theseparameters, the UE 984 may maintain communication with one or more ofthe neighboring cells. During this time, the UE 984 may maintain anActive Set, that is, a list of cells that the UE 984 is simultaneouslyconnected to (i.e., the UTRA cells that are currently assigning adownlink dedicated physical channel DPCH or fractional downlinkdedicated physical channel F-DPCH to the UE 984 may constitute theActive Set).

The modulation and multiple access scheme employed by the access network900 may vary depending on the particular telecommunications standardbeing deployed. By way of example, the standard may includeEvolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DOand UMB are air interface standards promulgated by the 3rd GenerationPartnership Project 2 (3GPP2) as part of the CDMA2000 family ofstandards and employs CDMA to provide broadband Internet access tomobile stations. The standard may alternately be Universal TerrestrialRadio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variantsof CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM)employing TDMA; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDMemploying OFDMA. UTRA, E-UTRA, UMTS, LTE, LTE Advanced, and GSM aredescribed in documents from the 3GPP organization. CDMA2000 and UMB aredescribed in documents from the 3GPP2 organization. The actual wirelesscommunication standard and the multiple access technology employed willdepend on the specific application and the overall design constraintsimposed on the system.

The radio protocol architecture may take on various forms depending onthe particular application. An example for an HSPA system will now bepresented with reference to FIG. 10.

Referring to FIG. 10, an example radio protocol architecture 1000relates to the user plane 1002 and the control plane 1004 of a userequipment (UE) or node B/base station. For example, architecture 1000may be included in a UE such as UE 102 including reliabilitydetermination component 130 (FIGS. 1 and 3). The radio protocolarchitecture 1000 for the UE and node B is shown with three layers:Layer 1 1006, Layer 2 1008, and Layer 3 1010. Layer 1 1006 is the lowestlower and implements various physical layer signal processing functions.As such, Layer 1 1006 includes the physical layer 1007. Layer 2 (L2layer) 1008 is above the physical layer 1007 and is responsible for thelink between the UE and node B over the physical layer 1007. Layer 3 (L3layer) 1010 includes a radio resource control (RRC) sublayer 1015. TheRRC sublayer 1015 handles the control plane signaling of Layer 3 betweenthe UE and the UTRAN.

In the user plane, the L2 layer 1008 includes a media access control(MAC) sublayer 1009, a radio link control (RLC) sublayer 1011, and apacket data convergence protocol (PDCP) 1013 sublayer, which areterminated at the node B on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 1008 including anetwork layer (e.g., IP layer) that is terminated at a PDN gateway onthe network side, and an application layer that is terminated at theother end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 1013 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 1013 also providesheader compression for upper layer data packets to reduce radiotransmission overhead, security by ciphering the data packets, andhandover support for UEs between node Bs. The RLC sublayer 1011 providessegmentation and reassembly of upper layer data packets, retransmissionof lost data packets, and reordering of data packets to compensate forout-of-order reception due to hybrid automatic repeat request (HARQ).The MAC sublayer 1009 provides multiplexing between logical andtransport channels. The MAC sublayer 1009 is also responsible forallocating the various radio resources (e.g., resource blocks) in onecell among the UEs. The MAC sublayer 1009 is also responsible for HARQoperations.

FIG. 11 is a block diagram of a Node B 1110 in communication with a UE1150, where the Node B 1110 may be base station 314 in FIG. 3, and theUE 1150 may be the UE 102 in FIGS. 1-2 which may include reliabilitydetermination component 130 in FIG. 1 for reducing cyclic redundancycheck (CRC) false detections at UE 102. In the downlink communication, atransmit processor 1120 may receive data from a data source 1112 andcontrol signals from a controller/processor 1140. The transmit processor1120 provides various signal processing functions for the data andcontrol signals, as well as reference signals (e.g., pilot signals).

For example, the transmit processor 1120 may provide cyclic redundancycheck (CRC) codes for error detection, coding and interleaving tofacilitate forward error correction (FEC), mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM),and the like), spreading with orthogonal variable spreading factors(OVSF), and multiplying with scrambling codes to produce a series ofsymbols.

Channel estimates from a channel processor 1144 may be used by acontroller/processor 1140 to determine the coding, modulation,spreading, and/or scrambling schemes for the transmit processor 1120.These channel estimates may be derived from a reference signaltransmitted by the UE 1150 or from feedback from the UE 1150. Thesymbols generated by the transmit processor 1120 are provided to atransmit frame processor 1130 to create a frame structure. The transmitframe processor 1130 creates this frame structure by multiplexing thesymbols with information from the controller/processor 1140, resultingin a series of frames. The frames are then provided to a transmitter1132, which provides various signal conditioning functions includingamplifying, filtering, and modulating the frames onto a carrier fordownlink transmission over the wireless medium through antenna 1134. Theantenna 1134 may include one or more antennas, for example, includingbeam steering bidirectional adaptive antenna arrays or other similarbeam technologies.

At the UE 1150, a receiver 1154 receives the downlink transmissionthrough an antenna 1152 and processes the transmission to recover theinformation modulated onto the carrier. The information recovered by thereceiver 1154 is provided to a receive frame processor 1160, whichparses each frame, and provides information from the frames to a channelprocessor 1194 and the data, control, and reference signals to a receiveprocessor 1170. The receive processor 1170 then performs the inverse ofthe processing performed by the transmit processor 1120 in the Node B1110. More specifically, the receive processor 1170 descrambles anddespreads the symbols, and then determines the most likely signalconstellation points transmitted by the Node B 1110 based on themodulation scheme.

These soft decisions may be based on channel estimates computed by thechannel processor 1194. The soft decisions are then decoded anddeinterleaved to recover the data, control, and reference signals. TheCRC codes are then checked to determine whether the frames weresuccessfully decoded. The data carried by the successfully decodedframes will then be provided to a data sink 1172, which representsapplications running in the UE 1150 and/or various user interfaces(e.g., display). Control signals carried by successfully decoded frameswill be provided to a controller/processor 1190. When frames areunsuccessfully decoded by the receive processor 1170, thecontroller/processor 1190 may also use an acknowledgement (ACK) and/ornegative acknowledgement (NACK) protocol to support retransmissionrequests for those frames.

In the uplink, data from a data source 1178 and control signals from thecontroller/processor 1190 are provided to a transmit processor 1180. Thedata source 1178 may represent applications running in the UE 1150 andvarious user interfaces (e.g., keyboard). Similar to the functionalitydescribed in connection with the downlink transmission by the Node B1110, the transmit processor 1180 provides various signal processingfunctions including CRC codes, coding and interleaving to facilitateFEC, mapping to signal constellations, spreading with OVSFs, andscrambling to produce a series of symbols.

Channel estimates, derived by the channel processor 1194 from areference signal transmitted by the Node B 1110 or from feedbackcontained in the midamble transmitted by the Node B 1110, may be used toselect the appropriate coding, modulation, spreading, and/or scramblingschemes. The symbols produced by the transmit processor 1180 will beprovided to a transmit frame processor 1182 to create a frame structure.The transmit frame processor 1182 creates this frame structure bymultiplexing the symbols with information from the controller/processor1190, resulting in a series of frames. The frames are then provided to atransmitter 1156, which provides various signal conditioning functionsincluding amplification, filtering, and modulating the frames onto acarrier for uplink transmission over the wireless medium through theantenna 1152.

The uplink transmission is processed at the Node B 1110 in a mannersimilar to that described in connection with the receiver function atthe UE 1150. A receiver 1135 receives the uplink transmission throughthe antenna 1134 and processes the transmission to recover theinformation modulated onto the carrier. The information recovered by thereceiver 1135 is provided to a receive frame processor 1136, whichparses each frame, and provides information from the frames to thechannel processor 1144 and the data, control, and reference signals to areceive processor 1138. The receive processor 1138 performs the inverseof the processing performed by the transmit processor 1180 in the UE1150. The data and control signals carried by the successfully decodedframes may then be provided to a data sink 1139 and thecontroller/processor, respectively. If some of the frames wereunsuccessfully decoded by the receive processor, thecontroller/processor 1140 may also use an acknowledgement (ACK) and/ornegative acknowledgement (NACK) protocol to support retransmissionrequests for those frames.

The controller/processors 1140 and 1190 may be used to direct theoperation at the Node B 1110 and the UE 1150, respectively. For example,the controller/processors 1140 and 1190 may provide various functionsincluding timing, peripheral interfaces, voltage regulation, powermanagement, and other control functions. The computer readable media ofmemories 1142 and 1192 may store data and software for the Node B 1110and the UE 1150, respectively. A scheduler/processor 1146 at the Node B1110 may be used to allocate resources to the UEs and schedule downlinkand/or uplink transmissions for the UEs.

Several aspects of a telecommunications system have been presented withreference to a W-CDMA system. As those skilled in the art will readilyappreciate, various aspects described throughout this disclosure may beextended to other telecommunication systems, network architectures andcommunication standards.

By way of example, various aspects may be extended to other UMTS systemssuch as TD-SCDMA, High Speed Downlink Packet Access (HSDPA), High SpeedUplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+) andTD-CDMA. Various aspects may also be extended to systems employing LongTerm Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A)(in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized(EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or othersuitable systems. The actual telecommunication standard, networkarchitecture, and/or communication standard employed will depend on thespecific application and the overall design constraints imposed on thesystem.

As noted above, such as with reference to FIGS. 1, 2 and 7, the abovedescribed managers, components, and other above described elements maybe implemented in hardware, software, or a combination thereof. Further,as noted, one or more processors may be used to implement these variousmanagers, components, and other elements in hardware, software or acombination thereof. For example, when implemented in software, one ormore processors may be used to execute such software. In accordance withvarious aspects of the disclosure, an element, or any portion of anelement, or any combination of elements may be implemented with a“processing system” that includes one or more processors. Examples ofprocessors include microprocessors, microcontrollers, digital signalprocessors (DSPs), field programmable gate arrays (FPGAs), programmablelogic devices (PLDs), state machines, gated logic, discrete hardwarecircuits, and other suitable hardware configured to perform the variousfunctionality described throughout this disclosure. Further, aspreviously noted, one or more processors may be used to execute softwareimplementing the above described managers, components, and/or otherelements. Software shall be construed broadly to mean instructions,instruction sets, code, code segments, program code, programs,subprograms, software modules, applications, software applications,software packages, routines, subroutines, objects, executables, threadsof execution, procedures, functions, etc., whether referred to assoftware, firmware, middleware, microcode, hardware descriptionlanguage, or otherwise.

The software may reside on a computer-readable medium. Thecomputer-readable medium may be a non-transitory computer-readablemedium. A non-transitory computer-readable medium includes, by way ofexample, a magnetic storage device (e.g., hard disk, floppy disk,magnetic strip), an optical disk (e.g., compact disk (CD), digitalversatile disk (DVD)), a smart card, a flash memory device (e.g., card,stick, key drive), random access memory (RAM), read only memory (ROM),programmable ROM (PROM), erasable PROM (EPROM), electrically erasablePROM (EEPROM), a register, a removable disk, and any other suitablemedium for storing software and/or instructions that may be accessed andread by a computer.

The computer-readable medium may also include, by way of example, acarrier wave, a transmission line, and any other suitable medium fortransmitting software and/or instructions that may be accessed and readby a computer. The computer-readable medium may be resident in theprocessing system, external to the processing system, or distributedacross multiple entities including the processing system. Thecomputer-readable medium may be embodied in a computer-program product.By way of example, a computer-program product may include acomputer-readable medium in packaging materials. Those skilled in theart will recognize how best to implement the described functionalitypresented throughout this disclosure depending on the particularapplication and the overall design constraints imposed on the overallsystem.

It is to be understood that the specific order or hierarchy of steps inthe methods disclosed is an illustration of exemplary processes. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the methods may be rearranged. The accompanyingmethod claims present elements of the various steps in a sample order,and are not meant to be limited to the specific order or hierarchypresented unless specifically recited therein.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. A phrase referring to“at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: a, b,or c” is intended to cover: at least one a; at least one b; at least onec; at least one a and at least one b; at least one a and at least one c;at least one b and at least one c; and at least one a, at least one band at least one c. All structural and functional equivalents to theelements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed under the provisions of 35 U.S.C. §112, sixth paragraph,unless the element is expressly recited using the phrase “means for” or,in the case of a method claim, the element is recited using the phrase“step for.”

What is claimed is:
 1. A method for reducing cyclic redundancy check(CRC) false detections at a user equipment (UE), comprising: receiving adata packet at the UE; determining whether a state metric value for eachof a plurality of vector elements of a last path metric vector of thedata packet is less than or equal to a first threshold; incrementing acounter when the state metric value of a vector element is less than orequal to the first threshold, wherein the counter is incremented foreach of the plurality of vector elements in which the state metric valueis less than or equal to the first threshold; determining whether thecounter is lower than a second threshold; and providing the data packetto an upper layer protocol entity of the UE when a CRC pass for the datapacket is determined and the counter is lower than the second threshold.2. The method of claim 1, wherein the state metric value indicates atotal path metric value from state zero at time zero to a state at endof the data packet.
 3. The method of claim 1, wherein the firstthreshold is set to a state metric value of state zero.
 4. The method ofclaim 1, wherein the second threshold is initially set to a value of256.
 5. The method of claim 4, further comprising: decreasing the secondthreshold when the counter is lower than the second threshold and theCRC pass for the data packet is determined.
 6. The method of claim 1,wherein a number of tail bits are present at the end of the data packet.7. The method of claim 6, wherein the tail bits include eight tail bits,and wherein each of the eight tail bits has a value of zero.
 8. Anapparatus for reducing cyclic redundancy check (CRC) false detections,comprising: means for receiving a data packet at the UE; means fordetermining whether a state metric value for each of a plurality ofvector elements of a last path metric vector of the data packet is lessthan or equal to a first threshold; means for incrementing a counterwhen the state metric value of a vector element is less than or equal tothe first threshold, wherein the counter is incremented for each of theplurality of vector elements in which the state metric value is lessthan or equal to the first threshold; means for determining whether thecounter is lower than a second threshold; and means for providing thedata packet to an upper layer protocol entity of the UE when a CRC passfor the data packet is determined and the counter is lower than thesecond threshold.
 9. The apparatus of claim 8, wherein the state metricvalue indicates a total path metric value from state zero at time zeroto a state at end of the data packet.
 10. The apparatus of claim 8,wherein the first threshold is set to a state metric value of statezero.
 11. The apparatus of claim 8, wherein the second threshold isinitially set to a value of
 256. 12. The apparatus of claim 11, furthercomprising: means for decreasing the second threshold when the counteris lower than the second threshold and the CRC pass for the data packetis determined.
 13. The apparatus of claim 8, wherein a number of tailbits are present at the end of the data packet.
 14. The apparatus ofclaim 13, wherein the tail bits include eight tail bits, and whereineach of the eight tail bits has a value of zero.
 15. A computer readablemedium storing computer executable code for reducing cyclic redundancycheck (CRC) false detections at a user equipment (UE), comprising: codefor receiving a data packet at the UE; code for determining whether astate metric value for each of a plurality of vector elements of a lastpath metric vector of the data packet is less than or equal to a firstthreshold; code for incrementing a counter when the state metric valueof a vector element of the plurality of vector elements is less than orequal to the first threshold, wherein the counter is incremented foreach of the plurality of vector elements in which the state metric valueis less than or equal to the first threshold; code for determiningwhether the counter is lower than a second threshold; and code forproviding the data packet to an upper layer protocol entity of the UEwhen a CRC pass for the data packet is determined and the counter islower than the second threshold.
 16. The computer readable medium ofclaim 15, wherein the state metric value indicates a total path metricvalue from state zero at time zero to a state at end of the data packet.17. The computer readable medium of claim 15, wherein the firstthreshold is set to a state metric value of state zero.
 18. The computerreadable medium of claim 15, wherein the second threshold is initiallyset to a value of
 256. 19. The computer readable medium of claim 18,further comprising: code for decreasing the second threshold when thecounter is lower than the second threshold and the CRC pass for the datapacket is determined.
 20. The computer readable medium of claim 15,wherein a number of tail bits are present at the end of the data packet.21. The computer readable medium of claim 20, wherein the tail bitsinclude eight tail bits, and wherein each of the eight tail bits has avalue of zero.
 22. A mobile apparatus to reduce cyclic redundancy check(CRC) false detections, comprising: a receiver configured to receive adata packet; and a processor coupled to a memory, the processorconfigured to: determine whether a state metric value for each of aplurality of vector elements of a last path metric vector of the datapacket is less than or equal to a first threshold; increment a counterwhen the state metric value of a vector element of the plurality ofvector elements is less than or equal to the first threshold, whereinthe counter is incremented for each of the plurality of vector elementsin which the state metric value is less than or equal to the firstthreshold; determine whether the counter is lower than a secondthreshold; and provide the data packet to an upper layer protocol entityof the UE when a CRC pass for the data packet is determined and thecounter is lower than the second threshold.
 23. The mobile apparatus ofclaim 22, wherein the state metric value indicates a total path metricvalue from state zero at time zero to a state at end of the data packet.24. The mobile apparatus of claim 22, wherein the first threshold is setto a state metric value of state zero.
 25. The mobile apparatus of claim22, wherein the second threshold is initially set to a value of
 256. 26.The mobile apparatus of claim 25, wherein the processor is furtherconfigured to: decrease the second threshold when the counter is lowerthan the second threshold and the CRC pass for the data packet isdetermined.
 27. The mobile apparatus of claim 22, wherein a number oftail bits are present at the end of the data packet.
 28. The mobileapparatus of claim 27, wherein the tail bits include eight tail bits,and wherein each of the eight tail bits has a value of zero.
 29. Themobile apparatus of claim 22, further comprising a user interface and adisplay.